UPS systems and methods using variable configuration modules

ABSTRACT

A UPS includes a first bridge circuit module, a second bridge circuit module, and a control circuit configured to operate the first bridge circuit module as an inverter and to selectively operate the second bridge circuit module as a bypass switch and a rectifier. The control circuit may be configured to operate the second bridge circuit module as bypass switch in a standby UPS mode and to operate the second bridge circuit module as a rectifier in an on-line UPS mode.

RELATED APPLICATIONS

The present application is a Continuation Application of U.S. patentapplication Ser. No. 15/478,600; filed Apr. 4, 2017 with the U.S. Patentand Trademark Office and claims the benefit of Continuation ApplicationU.S. patent application Ser. No. 13/936,741, filed Jul. 8, 2013 with theU.S. Patent and Trademark Office, the disclosures of which are herebyincorporated in their entireties by reference.

BACKGROUND

The inventive subject matter relates to power conversion apparatus andmethods and, more particularly, to uninterruptible power supply (UPS)apparatus and methods.

UPS systems are commonly used in installations such as data centers,medical centers and industrial facilities. UPS systems may be used insuch installations to provide backup power to maintain operation inevent of failure of the primary utility supply. UPS systems may have amodular structure including two or more UPS modules, each of which mayinclude, for example, a rectifier, an inverter and a DC/DC converter forinterfacing to a battery or other DC power source. The modules commonlyare designed to operate in parallel to provide scalable power capacity,e.g., the modules may be coupled in common to an AC source, a DC source(e.g., a battery) and/or a load. An example of such a modular UPS systemis the Eaton Power Xpert 9395 UPS system, which may be configured toinclude two or more uninterruptible power modules (UPMs), each of whichinclude a double conversion UPS circuit including a rectifier, inverterand battery converter coupled to a common DC bus.

Large data centers have proliferated with the advent of web services andcloud computing. Some newer large data centers occupy millions of squarefeet and house hundreds of thousands of servers. Typically powered bythe local grid, these centers may include backup power supply systemsincluding UPSs and diesel-electric backup generators to supportcontinued operation when utility power is lost. Energy consumption is amajor concern for such facilities, as some facilities are approachingthe 100 MW level. For such facilities, even a few percentage points ofefficiency can translate into significant expense.

Techniques for improving UPS efficiency have been developed. Forexample, some double-conversion UPS systems support high-efficiency or“eco” modes in which the rectifier and inverter are bypassed when theinput AC source meets certain criteria. Other solutions to increase datacenter energy efficiency, such as those described, for example, in U.S.Pat. No. 7,886,173 to Krieger et al., U.S. Pat. No. 7,560,831 to Whittedet al. and U.S. Pat. No. 8,344,546 to Sarti, include redundant powerdistribution techniques that avoid the use of traditional UPSarchitectures.

SUMMARY

Some embodiments of the inventive subject matter provide a systemincluding a plurality of module locations configured for installation ofuninterruptible power supply (UPS) modules and a control circuitconfigured to selectively support standby UPS and on-line UPS operationof modules installed at the plurality of module locations. The systemmay include a plurality of UPS modules installed in the plurality ofmodule locations and including at least one UPS module configured tooperate as a standby UPS. The plurality of UPS modules may furtherinclude at least one UPS module configured to operate as an on-line UPS.

In some embodiments, the plurality of UPS modules may share a commonarchitecture including a submodule location at which a submodule isinstallable and circuitry configured to support operation of a submodulein the submodule location as a rectifier for on-line UPS operation or asa bypass switch for standby UPS operation. The UPS modules may eachinclude an inductor assembly coupled to the submodule location andconfigured to operate as an energy storage device when a submoduleinstalled in the submodule location is operated as a rectifier and tooperate as a current limiter when a submodule installed in the submodulelocation is operated as a bypass switch.

Further embodiments provide a UPS system including a plurality of UPSmodule locations and at least one UPS module installed at acorresponding at least one of the plurality of UPS module locations. Theat least one UPS module includes an inverter submodule and a switchsubmodule configured to selectively bypass the inverter submodule. Theat least one UPS module may be configured to support a standby mode ofUPS operation wherein power is provided to a load coupled to the atleast one UPS module from an external AC source via the switch submodulein a first state and power is provided to the load from a battery viathe inverter submodule in a second state.

The switch submodule may be installed in a submodule location configuredto interchangeably support various types of submodules that provide atleast one different function than the switch submodule. The varioussubmodules may include a rectifier submodule.

In some embodiments, at least one UPS module may include a first UPSmodule installed at a first one of the UPS module locations andcomprising the inverter submodule and the switch submodule and thesystem may further include a second UPS module installed at a second oneof the UPS module locations and comprising an inverter submodule and arectifier submodule. The switch submodule and the rectifier submodulemay be installed in a common submodule location in the respective firstand second UPS modules.

In some embodiments, the at least one UPS module may include a first UPSmodule at a first one of the UPS module locations and configured becoupled to a first AC source and a second UPS module at a second one ofthe UPS module locations and configured to be coupled to a second ACsource. The first and second UPS modules may be configured to be coupledto respective first and second loads.

In some embodiments, a system includes a plurality of UPS modulelocations and first and second UPS modules installed at respective firstand second UPS module locations of the plurality of UPS module locationsand having respective first and second power outputs configured to becoupled to respective first and second power supply inputs of a datacenter equipment rack. At least one of the first and second UPS modulesincludes an inverter submodule and a switch submodule configured toselectively bypass the inverter module.

In some embodiments, both of the first and second UPS modules may beconfigured to provide a standby mode of UPS operation and the first andsecond UPS modules may be configured to receive power from respectivefirst and second AC sources. The system may further include at least onecomputer equipment rack having first and second power inputs connectedto respective ones of the first and second power outputs of the firstand second UPS modules.

In further embodiments, the first UPS module may be configured tosupport a standby mode of operation and the second UPS module may beconfigured to support an on-line mode of UPS operation. The system mayfurther include at least one first computer equipment rack coupled tothe first UPS module and at least one second computer rack coupled tothe second UPS module.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a UPS system according tosome embodiments.

FIG. 2 is a front elevation view of a module UPS system according tosome embodiments.

FIG. 3 is a schematic diagram illustrating a UPS module with a bridgecircuit submodule configured as a bypass switch according to someembodiments.

FIG. 4 is a schematic diagram illustrating a UPS module with an SCRswitch submodule configured as a bypass switch according to furtherembodiments.

FIG. 5 is a schematic diagram illustrating a UPS module with a bridgecircuit submodule configured to support rectifier operation according tosome embodiments.

FIG. 6 is a schematic diagram illustrating a UPS system with standby UPSmodules configured to provide power to a common load according to someembodiments.

FIG. 7 is a schematic diagram illustrating a UPS system with standby UPSmodules arranged in an A/B configuration according to some embodiments.

FIG. 8 is a schematic diagram illustrating a UPS system with standby andon-line UPS modules according to further embodiments.

FIG. 9 is a schematic diagram illustrating provision of power to a rowof server racks from a modular UPS system in an A/B configurationaccording to some embodiments.

FIG. 10 is a schematic diagram illustrating selective provision of powerto a row of server racks from standby and on-line modules of a modularUPS according to further embodiments.

FIG. 11 is a schematic diagram illustrating a UPS system according tofurther embodiments.

DETAILED DESCRIPTION

Specific exemplary embodiments of the inventive subject matter now willbe described with reference to the accompanying drawings. This inventivesubject matter may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein;rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventivesubject matter to those skilled in the art. In the drawings, likenumbers refer to like elements. It will be understood that when anelement is referred to as being “connected” or “coupled” to anotherelement, it can be directly connected or coupled to the other element orintervening elements may be present. As used herein the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the inventivesubject matter. As used herein, the singular forms “a”, “an” and “the”are intended to include the plural forms as well, unless expresslystated otherwise. It will be further understood that the terms“includes,” “comprises,” “including” and/or “comprising,” when used inthis specification, specify the presence of stated features, integers,steps, operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this inventive subject matterbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of thespecification and the relevant art and will not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

FIG. 1 illustrates a UPS system 100 according to some embodiments. Thesystem 100 includes a plurality of UPS modules 110 arranged in anintegrated fashion. For example, as shown in FIG. 2, UPS modules 110′may comprise respective modular cabinets configured to be joined to forman integrated UPS system 100′. As also shown in FIG. 2, the UPS system100′ may include additional components, such as may be housed in anadditional cabinet 120. Such components may include, for example,monitoring, communication and user interface circuitry, bypass switches,circuit breakers, and the like. It will be appreciated that modularphysical configurations other than that illustrated in FIG. 2 may beused in some embodiments. For example, rather than employing cabinetsthat are configured to be joined together as shown in FIG. 2, a modularUPS system accordingly to some embodiments may include a system chassisor similar structure configured to receive UPS modules and othercomponents in defined slots, compartments and/or other structures of thechassis.

Referring again to FIG. 1, at least one UPS module 110 may be configuredto operate as a standby (or “off-line”) UPS, which selectively providesAC power directly from an AC source, (e.g., a utility or generator) to aload connected to the UPS module 110 and, in the event of failure of theAC source, from an auxiliary power supply, such as one or morebatteries. As shown, the UPS may include a plurality of submodulesincluding, for example, an inverter submodule 112 and a switch submodule114. The inverter submodule 112 may be configured to generate AC powerfor delivery to a load from DC power supplied by a backup power source,such as a battery or bank of batteries. The battery(s) may be includedin the UPS system 100 and/or may be located external to the UPS system100 and connected thereto by cables or other conductors. The switchsubmodule 114 may be configured to provide a switchable bypass pathbetween the AC source and the load. Each of the UPS modules 110 may beconfigured as such, or other ones of the UPS modules 110 may beconfigured to provide other UPS operational modes, such as on-line(“double conversion”) modes, using different submodule configurations.

According to some embodiments, UPS modules, such as the UPS modules 110of FIG. 1, may share a common architecture that may be configured toprovide standby, on-line and/or other modes of UPS operation. FIG. 3illustrates a UPS module 300 having a modular arrangement includingfirst, second and third inductor assemblies 310, 320, 330, and first,second and third bridge circuit submodules 340, 350, 360. As show, eachof the bridge circuit submodules 340, 350, 360 may be configured asswitching devices (e.g., IGBTs) coupled in a half-bridge legarrangement. It will be appreciated that the bridge circuit submodules340, 350, 360 may each include one more half-bridge legs to supportsingle or 3-phase operation.

The second bridge circuit submodule 350 is coupled to an AC output ofthe UPS module 300 via the second inductor assembly 320 and isconfigured to provide inverter operation in conjunction with the secondinductor assembly 320. The third bridge circuit submodule 360 shares aDC bus connection with the second bridge circuit submodule 350 andoperates in conjunction with the third inductor assembly as a DC/DCbattery converter.

The first bridge circuit submodule 340 is configured to provide a bypassswitch functionality. The first bridge circuit submodule 340 may providea relatively low loss bypass path between an AC input of the UPS module300 and an AC output of the UPS module 300 such that, under normalconditions, AC power is delivered to the load without conversion withinthe UPS system 300. The first inductor assembly 310 is coupled in serieswith the first bridge circuit submodule 340. A control circuit 370 isconfigured to control the bridge circuit submodules 340, 350, 360 andother components of the UPS module 300.

FIG. 4 illustrates an alternative arrangement for a standby UPS module400. The UPS module 400 includes inductor assemblies 310, 320, 330 andinverter and battery converter bridge circuit submodules 350, 360 asdescribed above with reference to FIG. 3. However, in place of thebridge circuit submodule 340 of FIG. 3, the UPS module 400 includes abypass switch implemented using a SCR-based static switch submodule340′. A control circuit 370′ may be configured to monitor and controlthe static switch submodule 340′ and other components of the UPS module400.

Referring to FIG. 5, an on-line (double conversion) UPS module 500 mayuse the same submodule architecture as the standby modules illustratedin FIGS. 3 and 4. In an on-line UPS module 500, the second and thirdbridge circuit submodules 350, 360 are still configured to provideinverter and battery converter operation but, instead of beingconfigured to operate as a bypass switch, the first bridge circuitsubmodule 340 is configured to support operation, in conjunction withthe first inductor assembly, as a boost rectifier that shares a DC busconnection with the second and third bridge circuit submodules 350, 360.

As noted above, the UPS modules 300, 400, 500 described above may sharea common architecture that allows the modules to be flexibly used in aUPS system to support standby, on-line and other operational schemes. Itwill be appreciated that the UPS modules 300, 400, 500 may, for example,use replaceable submodules, such as the bridge circuit submodule 340 andthe SCR submodule 340′, which may, for example, be interchangeablyinstallable in designated locations, such as in predeterminedmechanical/electrical structures within a UPS module. Such locationsmay, for example, be configured to provide pluggable or other flexibleelectrical connections for submodules. Submodules installed in suchlocations may use common form factors, control circuitry and coolingsystems. For example, the control circuitry of a UPS module may beconfigured to flexibly support operation of different types ofsubmodules in a giving submodule location. For, the control circuits370, 370′, 370″ of FIGS. 3-5 may be implemented using a common controlcircuit that may be flexibly configured, e.g., using softwareand/reconfigurable hardware, to support the operation of different typesof submodules in the various submodule locations. The control circuits370, 370′, 370″ may include, for example, contactors and/or otherdevices used to control connectivity between the submodules and othercomponents of the UPS modules.

Configuration of electrical interconnections to, from and within thesubmodules to support various operations, e.g., as a bypass switch or arectifier, may be achieved by changing wiring manually and/or byactuating switching devices (e.g., contactors) to provideinterconnections that support the desired use. In some embodiments,submodules may themselves be reconfigurable to perform various functionsby wiring changes and/or actuation of switches within the submodules.For example, in some embodiments, a bridge circuit submodule may bereconfigurable to provide the bypass switch and rectifier operationalmodes described for the submodules 340, 340′ of FIGS. 3 and 5.

Modular UPS systems according to some embodiments may be used to provideflexible UPS system arrangements. For example, referring to FIG. 6, aUPS system 600 may include first and second standby UPS modules 300 a,300 b along the lines described above with reference to FIG. 3. Asshown, the first and second UPS modules 300 a, 300 b may be coupled incommon to a load and to a battery. Respective AC sources, such as autility source and a local generator (e.g., a diesel/electric generatorset), may be coupled to respective ones of the first and second UPSmodules 300 a, 300 b to provide source redundancy. Under normalconditions, power may be supplied from the AC utility directly to theload via the bypass switch submodule 340 of the first UPS module 300 a.Upon failure of the utility source, the load may be carried by theinverter submodule 350 of the first UPS module 300 until the localgenerator comes on line and the load is transferred to the switch module340 of the second UPS module 300 b. This arrangement may supportrelatively high-efficiency operation, as power may be directly providedto the load from the AC sources without passing through adouble-conversion rectifier/inverter combination.

FIG. 7 illustrates a UPS system 700 using first and second standby UPSmodules 300 a, 300 b configured to support an “A/B” dual powerconfiguration, such as might be used with dual power input racks in adatacenter application. Some server racks are configured with redundantdual power supplies (“A” and “B”) that are designed to be fed fromseparate power sources. The first standby UPS module 300 a may becoupled to an “A” source and configured to provide power to “A” powerinputs of one or more racks, while the second standby UPS module 300 bmay be coupled to a “B” source and configured to provide power to “B”power inputs of the one or more racks. Such an arrangement isillustrated in FIG. 9, which shows connection of first and second UPSmodules 300 a, 300 b of a UPS system 700 along the lines shown in FIG. 7to a row of server racks 910. The UPS system 700 may support redundancyfor the AC sources and the rack power supplies, with battery backupavailable for either of the UPS modules 300 a, 300 b. This arrangementmay also support relatively high-efficiency operation, as power may bedirectly provided to the load from the AC sources without passingthrough a double-conversion rectifier/inverter combination.

UPS systems according to some embodiments may also support combinationsof standby and on-line UPS modules. FIG. 8 illustrates a UPS system 800including a standby UPS module 300 along the lines illustrated in FIG. 3and an on-line UPS module 500 along the lines illustrated in FIG. 5. Afirst source and a first load are coupled to the standby UPS module 300.A second source and a second load are coupled to the on-line UPS module500. The first and second sources may be the same or different.

An example application for the UPS system 800 is illustrated in FIG. 10,wherein the standby UPS module 300 provides power to first racks 1010 a,while the on-line UPS module 500 provides power to second racks 1010 b.The first racks 1010 a may, for example, house servers that performcomputing tasks that are less critical and/or may be mirrored orotherwise backed up by computing resources located elsewhere, such asthe case in some cloud computing applications. For such loads, reducingaggregate energy consumption may be more important thanreliability/availability of a given rack/server. The standby UPSarrangement can reduce the number of loss-incurring components in thepower path in comparison to on-line configurations while still providingbackup power capabilities. The second racks 1010 b may house serversthat perform more critical tasks for which reliability and availabilityis more important which require additional power conditioning and otherperformance characteristics that an on-line UPS configuration mayprovide. The UPS system 800 may also include a separate static bypassswitch to provide bypass capability for the on-line UPS module 500. Sucha bypass switch may be used, for example, to support higher efficiencymodes in which the bypass is use to provide a reduced-loss path to theload when the source is within nominal parameters.

The modular architecture of the UPS module 300 can provide additionalbenefits that may not be available in conventional direct-feedarrangements. For example, the inductor assembly 310, which serves as anenergy storage device in on-line UPS module configurations, can serve asa current limiter in standby UPS module configurations. In addition,current and/or voltage sensors and monitor use for rectifier control inon-line UPS module configurations can be dual-purposed to providecurrent and/or voltage monitoring in standby UPS module configurations.In some embodiments, using a bridge circuit submodule as a bypass switchfor standby UPS operation may also afford the opportunity for moresophisticated control of power input than available in conventionaldirect-feed configurations.

FIG. 11 illustrates a UPS system 1100 with a modular architectureaccording to further embodiments. The UPS system 1100 includes aplurality of UPS module locations at which UPS modules 1110 may belocated. For example, as explained above with reference to FIG. 2, theUPS module 1110 may be cabinet-like assemblies configured to be joinedto form an integrated unit or may be configured to be installed in slotsor similar structures in a common chassis. The UPS system furtherincludes at least one auxiliary module 1120. The auxiliary module 1120may be configured to receive functional submodules that may be selectedbased on functional requirements of the UPS modules 1110. For example,if one or more of the UPS modules 1110 is a standby UPS module, theauxiliary module 1120 may have, for example, one or more concurrentmaintenance submodule 1124 installed therein, which may include circuitbreakers and/or other devices that allow selective disconnection of thestandby UPS module from the power source and/or load while enablingother UPS modules 1110 in the system 1100 to continue operation. Asfurther shown, the auxiliary module 1120 may also be configured toreceive one or more submodules that support operation of on-line UPSmodules, such as a static bypass switch submodule 1122.

In the drawings and specification, there have been disclosed exemplaryembodiments of the inventive subject matter. Although specific terms areemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation, the scope of the inventive subject matterbeing defined by the following claims.

That which is claimed:
 1. An uninterruptible power supply (UPS)comprising: an input; an output; a converter circuit coupled to theoutput; a half-bridge circuit coupled between the input and the outputand configured to provide a bypass of the converter circuit, thehalf-bridge circuit comprising first and second transistors having firstterminals coupled to one another and second terminals coupled to oneanother; and a control circuit configured to operate the half-bridgecircuit.
 2. The UPS of claim 1: wherein the input comprises an AC input;wherein the output comprises an AC output; and wherein the convertercircuit comprises an inverter.
 3. The UPS of claim 2, further comprisingat least one inductor coupled between the AC input and the half-bridgecircuit.
 4. The UPS of claim 3, wherein the first terminals of the firstand second transistors are coupled in common to the at least oneinductor and the second terminals of the first and second transistorsare coupled in common to the AC output.
 5. The UPS of claim 3, whereinthe at least one inductor comprises first and second inductors coupledin parallel.
 6. The UPS of claim 1, wherein the first terminals of thefirst and second transistors are coupled in common to the input and thesecond terminals of the first and second transistors are coupled incommon to the output.
 7. The UPS of claim 1, wherein the half-bridgecircuit comprises a first half-bridge circuit and wherein the convertercircuit comprise a second half-bridge circuit comprising third andfourth transistors having first terminals coupled to one another andsecond terminals coupled to respective first and second DC buses.
 8. TheUPS of claim 7, wherein the converter circuit further comprises a thirdhalf-bridge circuit coupled to the second half-bridge circuit by thefirst and second DC buses and comprising fourth and fifth transistorshaving first terminals coupled to one another and second terminalscoupled to respective ones of the first and second DC buses.
 9. The UPSof claim 7, wherein the first half-bridge circuit comprises a modulereconfigurable to operate as a rectifier.
 10. The UPS of claim 1,wherein the half-bridge circuit comprises a module reconfigurable tooperate as a rectifier.